As the executor of life activities, proteins exert their specific biological functions through interactions such as forming protein complexes. The localization effects, crowding effects, and organelle microenvironments within cells are crucial for maintaining the structure and function of protein complexes. Therefore, it's important to analyze protein complexes accurately.
　　Recently, a research team led by Prof. ZHANG Lihua from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has developed a glycosidic-bond-based mass-spectrometry-cleavable cross-linker, which improves the data analysis throughput and identification accuracy of cross-linking information with good amphiphilicity and biocompatibility. It enables in-vivo cross-linking of protein complexes in live cells and achieves large-scale and precise analysis.
　　This study was published in Angewandte Chemie International Edition on March 30.
　　Chemical cross-linking mass spectrometry (CXMS), especially in-vivo CXMS, is a large-scale analysis of in-situ conformation and interaction interface of protein complexes in living cells. However, in-vivo CXMS in living cells faces challenges such as high cell disturbance and complex spectra retrieval of cross-linked peptides.
　　In this study, the researchers incorporated glycosidic bonds into the design of functional cross-linkers based on the high biocompatibility of glucose molecules and the mass spectrometry cleavable feature of glycosidic bonds. They screened and obtained trehalose, a highly biocompatible molecule, as the skeleton molecule and developed a mass spectrometry cleavable cross-linker, trehalose disuccinimidyl succinate (TDS).
　　This cross-linker showed superior cell viability maintenance compared to currently reported membrane-permeable chemical cross-linkers and enabled efficient cross-linking of protein complexes in cells under low disturbance conditions.
　　The researchers found that low-energy glycosidic bond-high-energy peptide bond mass spectrometry selective fragmentation mode reduced the analysis complexity of the cross-linked peptide fragment spectra, significantly improving the efficiency and accuracy of cross-linked peptide identification.
　　They identified conformation of 1453 proteins corresponding to over 3,500 cross-linked peptide pairs, and 843 protein-protein interaction information from Hela cells.
　　"We have accurately realized in-vivo cross-linking and global analysis of protein complexes in live cells," said Prof. ZHANG. "And we provided an important toolkit for exploring the interaction sites of protein function regulation in live cell microenvironment."
　　This work was supported by the National Natural Science Foundation of China, the National Key R&D Program, and the Youth Innovation Promotion Association of CAS.

　　Water oxidation reaction involves a four-electron and four-proton transfer process, which requires an uphill energy transformation and limits the efficiency of the overall photocatalytic water splitting reaction.
　　Although loading appropriate water oxidation cocatalysts can enhance the performance of water oxidation reactions, the interfacial barrier between the semiconductor and the water oxidation cocatalyst can impede the transfer and utilization of photogenerated charges.
　　Recently, a research team led by Profs. LI Can and LI Rengui from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has developed a strategy to controllably assemble a charge-transfer mediator in photocatalysis, which could increase surface charge-transfer efficiency and photocatalytic water oxidation activity.
　　This study was published in Angew. Chem. Int. Ed. on March 23.
　　Inspired by natural photosynthesis, the researchers employed partially oxidized graphene (pGO) as a charge-transferring mediator on the hole-accumulating facets of lead chromate (PbCrO4) photocatalyst. The pGO could be selectively assembled on the hole-accumulating facets of PbCrO4 by an ultrasonic deposition process, and cobalt-complex Co4O4 molecules could be anchored on the pGO as water oxidation cocatalyst.
　　Partially oxidized graphene operates as a charge-transfer mediator between the water oxidation cocatalyst (Co4O4) and the hole-accumulating {-101} facets of PbCrO4 (Image by JIANG Wenchao)
　　Based on techniques such as surface photovoltage spectroscopy, they confirmed that introducing the pGO charge transfer mediator between the hole-accumulation facets of PbCrO4 and Co4O4 molecules could effectively suppress charge recombination at the interface, thus prolonging the lifetime of photogenerated charges and enhancing the photocatalytic water oxidation performance.
　　"This strategy of rationally assembling charge transfer mediator provides a feasible way for accelerating charge transfer and charge utilization in semiconductor photocatalysis," said Prof. LI Rengui.
　　This study was supported by the Fundamental Research Center of Artificial Photosynthesis (FReCAP) of the National Natural Science Foundation of China, and the National Key Research and Development Program of China.

　　Hydrogen cyanide (HCN) featured with high volatility and high adsorption is a common toxic and hazardous gas. Traces of HCN are also found in human exhaled breath. Unusual high HCN concentration in the breath of cystic fibrosis (CF) patients is associated with Pseudomonas aeruginosa (PA) infection. Therefore, the development of a highly sensitive online HCN measurement in exhaled breath can enable rapid screening for PA infection in CF patients.
　　Recently, a research group led by Prof. LI Haiyang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has developed a flow-assisted photoionization mass spectrometry method for profiling hydrogen cyanide in exhaled breath.
　　The study was published in Analytical Chemistry on April 4.
　　Schematic diagram of the vacuum ultraviolet lamp-based negative photoionization source and detected human exhaled HCN profile (Image by Wen Yuxuan)
　　"HCN is easily soluble in water and highly adsorbed on device surfaces, so sensitivity and response speed are main challenges for directly measuring HCN in exhaled breath at high humidity presents," said Prof. CHEN Ping, co-corresponding authors of this study.
　　The researchers developed a method by utilizing a self-developed atmospheric pressure negative photoionization time-of-flight mass spectrometer instrument and improved the sensitivity and time resolution of direct HCN measurements in exhaled breath. This method enabled real-time tracking of HCN concentrations in a single exhaled breath, which could provide an effective means for early screening of CF patients with PA infection.
　　They proposed to use helium shield gas within the mass spectrometry ionization source. This approach reduced the effect of high humidity on ionization, improved ion transport efficiency, and thus enhanced HCN detection sensitivity.
　　Moreover, they improved the sampling system by shortening the sampling line and adding a gas purging process to effectively reduce HCN adsorption residue and improve time resolution. This method achieved a limit of detection of 0.3 ppbv and a resolution time of 0.5 s.
　　By utilizing this method, the researchers tracked the changes in the single exhaled HCN profiles of volunteers before and after gargling. The resulting profiles clearly showed an early peak and a stable end-tidal plateau, representing the concentration of the oral cavity and end-tidal gas， respectively.
　　"The new method demonstrated good resistance to interference and high accuracy in HCN quantification. It has potential application in the detection of PA infection in CF patients," said Prof. LI.

　　Two notable metal oxide structures, spinel-type oxide and solid solution-type oxide, are widely used in Oxide-Zeolite (OXZEO) bifunctional catalysts for CO/CO2 hydrogenation reactions.
　　Identifying the crystallographic structure sensitivity of catalysts in chemical reactions is helpful to the rational design of catalysts. However, direct and convincing study to correlate the crystal structure of oxide to its catalytic performance is still lacking.
　　Recently, a joint research team led by Prof. BAO Xinhe, Prof. PAN Xiulian, Assoc. Prof. JIAO Feng and Prof. XIAO Jianping from the Dalian Institute of Chemical Physics(DICP) of the Chinese Academy of Sciences (CAS) has observed the strongly crystal phase-dependent activity of MnGaOx in direct syngas conversion.
　　This study was published in Angewandte Chemie International Edition on April 18.
　　"The main challenge to observing the crystal structure of oxide is the lack of a well-defined material-synthesis method to obtain metal oxides with the same element components but different crystallographic structures," said JIAO.
　　In this study, the researchers found co-precipitation method and hydrothermal method could synthesize bimetallic oxides, which were composed of amorphous MnO2 and Ga2O3 with hexagonal close-packed (HCP) or Face centered-cubic (FCC) crystal phase, respectively. More interestingly, they found that the HCP oxide remained unchanged as HCP MnO-Ga2O3 solid solution oxides after reduction under H2 or CO, while the FCC solid solution oxide transformed into FCC spinel structure, where reduced Mn2+ took the A-site of AB2O4 spinel structure.
　　Crystal-phase-dependent of syngas conversion activity of MnGaOx-SAPO-18 (Image by BAI Bing and JIAO Feng)
　　They obtained 40% CO conversion, 81% light olefins selectivity, and 0.17 g·gcat-1·h-1 space-time yield of light olefins with the combination of FCC MnGaOx-Spinel and SAPO-18. In comparison, they obtained a much inferior activity with solid solution MnGaOx with a similar chemical composition.
　　They further proved that the superior activity of MnGaOx-Spinel was attributed to its higher reducibility and the presence of coordinatively unsaturated Ga3+ site, which facilitated the dissociation of the C-O bond via a more efficient ketene-acetate pathway to light olefins.
　　"Our findings may further optimize metal oxides for OXZEO syngas conversion,"said Prof. PAN.

　　Water splitting is one of renewable and environmentally-friendly energy sources.
　　Understanding the reactions between water molecules and isolated metal atoms/clusters, which can boost catalytic performance, is helpful to reveal the microscopic mechanisms of water splitting at molecular level. However, the experimental investigation of the reactions between water molecules and neutral metals is challenging due to the neutral clusters, lack of charges, are hard to be detected.
　　Recently, a research team led by Prof. JIANG Ling and Dr. LI Gang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences studied the reactions of water with neutral vanadium (V) dimer by using a size-specific infrared-vacuum ultraviolet spectroscopy, and realized water splitting.
　　This study was published in The Journal of Physical Chemistry Letters on April 17.
　　The researchers measured infrared spectra for the neutral V2O3H4 and V2O4H6 complex in the 2800-4100 cm-1 spectral region by recently-developed infrared spectroscopy using a tunable vacuum ultraviolet free electron laser (VUV-FEL).
　　They found that V2O3H4 and V2O4H6 had unexpected V2(μ2-OH)(μ2-H)(η1-OH)2 and V2(μ2-OH)2(η1-H)2(η1-OH)2 structures, indicating the exist of water splitting. Moreover, they indicated that the water splitting by V2 was both thermodynamically exothermic and kinetically facile in the gas phase.
　　"Our study provides new avenues toward systematic understanding of water splitting by a large variety of single-cluster catalysts," said Prof. JIANG.

　　Multi-electron reaction is defined as a reaction in which more than one electron is transferred per active materials molecule. VOPO4, a typical class of multi-electron reaction cathode materials with V4+/V5+ and V3+/V4+ multiple redox couples, possesses a higher potential with the introduction of more electronegative (PO4)3- anion, which can provide enhanced energy density.
　　However, the vanadium phosphates suffer from unsatisfactory performance, especially for high rate capability due to the bulk diffusion process and low intrinsic electrical conductivity.
　　Recently, a research team led by Prof. WU Zhong-Shuai from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences has developed a high-performance 2D pseudocapacitive multi-electron reaction lithium storage materials via V4+ defect engineering for solid-state lithium metal batteries with high energy density and high power density.
　　This study was published in Advanced Energy Materials on April 9.
　　Schematic of Li||ETPTA-LiClO4-SSE||VOPO4 solid-state lithium metal battery and the corresponding Ragone plot（Image by XING FeiFei）
　　The researchers realized the high-rate pseudocapacitive cathode with multi-electron reaction chemistry by regulating V4+ defect in VOPO4. The as-prepared 2D VOPO4/graphene nanosheets not only had an ultrathin nanosheet structure to improve electronic and ionic conductivity, but also adjusted the uniformity of multi-electron reactions and reduced polarization by controlling the content of V4+ defects.
　　The pseudocapacitive multi-electron reaction cathode exhibited a high capacity of 313 mAh g-1 at 0.1 C and maintained a capacity of 116 mAh g-1 at an ultrafast rate of 50 C.
　　The researchers further synthesized a novel UV-curable solid electrolyte (ETPTA-LiClO4-SSE), which had an ion conductivity of 0.99 mS cm-1 at room temperature. This was much higher than that of polyethylene oxide solid electrolytes (~10-6 S cm-1). The assembled Li||ETPTA-LiClO4-SSE||VOPO4 solid-state lithium metal battery presented a high energy density of 85.4 Wh kg-1 and a high power density of 2.3 kW kg-1.
　　What's more, the as-assembled solid-state lithium metal batteries pouch cell displayed good flexibility and safety.
　　"Our study provide a new avenue for the development of 2D pseudocapacitive fast-charging cathodes with multi-electron chemistry for high specific energy and high power lithium metal batteries," said Prof. WU.
　　This study was supported by the National Natural Science Foundation of China, and DICP Innovation Fund.